The present invention relates generally to wireless communications, and more particularly, to a system for measuring the Ricean stastical nature of radio propagation in real time.
A channel having two fundamental components comprised of a fixed component and a fluctuating multipath component (i.e., the addition of several scattered versions of the original beam), can be characterized as having a propagation environment that is Ricean in statistical nature. The K-factor of a Ricean channel is the ratio of the power received in the fixed component, to the total power received via indirect scattered paths. Knowledge of the Ricean K-factor is important in the understanding of fixed and other wireless channels. It is a statistical computation that helps to implement link budget calculations by allowing estimates of fast fading margins, i.e., it enables the description of the fast fading envelope's distribution. It also provides useful information to provide efficient power control. Field technicians can use K-factor readings to estimate the condition of the channel, and to determine the bit error rate of the channel. Accordingly, the ability to implement timely and accurate measurements of the K-factor is a highly desirable characteristic in a wireless communication system. Measurements of the K-factor have traditionally been made by way of a network analyzer that compares transmitted and received waveforms. An example of which is disclosed in J. P. M. G. Linnartz (Ed.), How to measure the Ricean K-factor, in Wireless Communication, The Interactive Multimedia CD-ROM, Edition 1999, Baltzer Science Publishers, Amsterdam, 1999. Using a network analyzer for this application has drawbacks including high cost and impractical implementation. Network analyzers are typically bulky devices that cannot be embedded into a system. Moreover, measurements obtained in this manner cannot be used to perform real-time tasks as the process is more akin to a “laboratory testing” environment.